Patent GB-893563-A (GB)
Title: Improvements in or relating to apparatus for producing cathode ray tube displays
Inventor: BOWLES DONALD CLIVE
IPC: H03K4/02
Filed: 1959-05-11
Abstract: 893,563. Cathode-ray oscilloscopes; transistor pulse circuits. BUSH & RANK CINTEL Ltd. May 11, 1960 [May 11, 1959 (2)], Nos. 16048/59 and 16049/59. Classes 40(6) and 40(7). To form a cathode-ray (C.R.) tube display, Fig. 1 (Prov. 16049/59) showing lines L advancing repetitively to a vanishing point P, means generate a staircase voltage waveform in which the levels differ in accordance with an exponential function, the peak amplitude of the waveform is varied periodically over a range equal to the amplitude of the largest step, and the staircase waveform is applied to control the deflection of the C.R. tube beam in a direction perpendicular to that of lines L and to control their lengths. C. R. oscilloscopes and transistor pulse circuits, Prov. 16049/59, Figs. 2, 3, 4 and 5. Trigger pulse trains, Figs. 3A, 3B, are applied to terminals 2, 3 respectively of unit 1 which includes a sawtooth, Fig. 3C, generator and produces a train, Fig. 3D, of exponential staircase waveforms for vertical deflection generator 4 and for beam intensity-modulation pulse generator 7 For each 'tread' of the staircase waveform, Fig. 4E, there are provided a pair of pulses, Fig. 4F, sawtooth 'X' C.R. beam deflection waveforms, Fig. 4G, being triggered by the early and late pulses of each pair by generators 10, 11 respectively. C.R. beam intensity-modulation pulses, Fig. 4H, the width of the pulses of a pair being proportional to the amplitude of the corresponding staircase tread, are generated by the transistor circuit shown in Fig. 5, the staircase voltage, Fig. 4E, being applied at terminal 21 and early and late pulses, Fig. 4F, being applied at terminals 22 and 23 respectively. Transistors 29, 33 form a cross-coupled mono-stable multivibrator triggered via transistor 26 circuit, the staircase voltage acting as a catcher potential via diode 31 for capacitor 30, the latter also being connected to a constant-current circuit comprising transistors 37, 38 in a cascaded bootstrap circuit and to transistor 33 base via diode 32 which prevents undesired effects arising from the Zener diode action of the base diode of the transistor; waveform, Fig. 4H, appears at the collector of transistor 33. Transistor exponential staircase voltage generator, Prov. 16048/59 Figs. 2 and 3. In this arrangement pulses, Fig. 2A, are applied to terminal 11 and sawtooth, Fig. 2B, to terminal 17. Height-modulated pulses, Fig. 2C, ensue across the emitter load 14 of transistor 13 and charge capacitor 19 via diode 18. In the inter-pulse intervals the capacitor discharges through resistor 20, Fig. 2D. Diode bridge network 23 switches the instantaneous voltage on capacitor 19 to capacitor 26, the switching positive and negative-going pulses, e.g. Fig. 2E, being applied at terminals 31, 32. Capacitor 26 is connected to output terminal 36 via cascaded emitter-follower transistors 33, 34. A brief initial step X, Fig. 2F, may occur but is not related to the exponential staircase voltage output and can occur only when the C.R. tube beam is blanked. General. All the transistors are of the NPN type. Specifications 873,321 and 874,255 are referred to.